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You're incorrect. People do want to restrict inaccurate diagnostic tests. The false positive rate for some Down syndrome tests runs at around 5%. True negative
by bhickey 16y ago
You're incorrect. People do want to restrict inaccurate diagnostic tests.
The false positive rate for some Down syndrome tests runs at around 5%. True negative is around 80% (Quad test). The rate of Down syndrome pregnancies amongst 40 year olds is approximately 1%. If the quad test says that a fetus has Down syndrome, the probability that it actually does is only 14%. The story is even worse amongst younger mothers (0.1% disease incidence) -- 1.6% true positive rate. Given that the pregnancy termination given a Down syndrome diagnosis is 93% we should care about these numbers.
I can go on. Breast cancer testing in women who aren't in a risk population is similarly dangerous. Biopsies do carry small risks. Most men with prostate cancer will probably die of something other than prostate cancer. If we treat it, it often leads to urinary incontinence and erectile dysfunction.
Bad tests are frankly dangerous and should be subject to regulation.
- AngryParsley 16y agoGiven that the pregnancy termination given a Down syndrome diagnosis is 93% we should care about these numbers. A 14-16x greater risk of Down syndrome seems to me like a good reason to terminate a pregnancy. I agree that more accurate tests would be better. Breast cancer testing in women who aren't in a risk population is similarly dangerous. Biopsies do carry small risks. I do not know enough about this topic to form a useful opinion. That sounds reasonable though. Most men with prostate cancer will probably die of something other than prostate cancer. Isn't this a problem with overzealous treatment, not inaccurate testing? Bad tests are frankly dangerous and should be subject to regulation. I'm pretty hands-off about genetic testing, since there's not much of a direct risk involved in spitting in a tube. Most of the risk is from decisions based on currently-incomplete scientific knowledge. As long as people are properly educated about how to judge risks and uncertainty, I think letting them see their own genes is fine.
- carbocation 16y agoI don't disagree with your points in the abstract. I could envision a highly logical society in which learning that you had prostate cancer didn't prompt an immediate desire to get that cancer treated. Even then, why get the test at all if it won't change management? In other words, if you're not going to do anything differently based on a positive or negative test, the test is simply a waste of money, and potentially harmful.
- AngryParsley 16y agoEven then, why get the test at all if it won't change management? Well, quite a few genetic tests do change management (Warfarin sensitivity, antidepressant response, various differences in activity of various enzymes.), but I even want to know about test results that don't. I want to know if I have ApoE4 or some other gene that highly correlates with currently-incurable diseases. If I have a better idea of my life expectancy and my future quality of life, I can change my behavior today. I would live my life quite differently if I thought I my brain would rot in 20 years.